Lazrit
Material

Laser-Cut MDF Files: Char Control, Bridges, Safe Settings

MDF cuts straight and engraves dark, but the urea-formaldehyde binder smokes hard and chars at the edge. Thin features collapse into a dark crumb. Lazrit's MDF profile uses the same 3 mm thickness as wood, but expects you to design for the char — minimum detail 1 mm, minimum bridge 2 mm, and a strong recommendation to engrave outlines if you want crisp lines without burnt halos.

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Recommended cut settings

SettingDefault
Default thickness3 mm
Minimum bridge width2 mm
Minimum detail1 mm

Why MDF chars so much

MDF is wood fibers held together with adhesive. The laser vaporizes both — but the adhesive emits a sticky tar that re-deposits on the edge and turns black. There's no way to design around the chemistry. You can mitigate with masking tape on the top face and good air assist.

Recommended settings

3 mm MDF on a 60 W CO2: ~8 mm/s at 90% power for cut, ~250 mm/s at 20% power for engrave. Single pass when possible — repeated passes deepen the char ring.

How Lazrit prepares MDF files

Same pipeline as wood: trace, validate topology, auto-bridge, separate engrave layers. The MDF profile is conservative about thin features — anything under 1 mm gets flagged, and you'll see warnings on sharp inner corners that tend to char more than open features.

Finishing MDF cuts

A quick sand on the edge knocks down the char crumbs. Sealing with primer before painting hides the dark line.

Frequently asked questions

Why is the engrave so much darker on MDF than birch ply?

The binder. MDF carbonizes more readily and the dark deposit re-fuses onto the surface. Useful for high-contrast signage, painful for fine engraving.

Can Lazrit reduce char automatically?

No — char is a power/speed/air assist problem at cut time, not a vector problem. Lazrit will produce a clean file; charring is on you and the machine.

What's the minimum feature size on MDF?

1 mm. Smaller features tend to vaporize before they're fully cut, leaving a fragile crumb instead of a clean edge.

Do I need bridges on MDF?

Yes, on any island. MDF off-cuts are heavy enough to fall fast and chip neighboring features.

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